The applicable FAR may be found at faa.gov->regulations and policies->current regulations->FAR 61.129i which says in part:
(i) Permitted credit for use of a flight simulator or flight training device. (1) Except as provided in paragraph (i)(2) of this section, an applicant who has not accomplished the training required by this section in a course conducted by a training center certificated under part 142 of this chapter may:
(i) Credit a maximum of 50 hours toward the total aeronautical experience requirements for an airplane or powered-lift rating, provided the aeronautical experience was obtained from an authorized instructor in a flight simulator or flight training device that represents that class of airplane or powered-lift category and type, if applicable, appropriate to the rating sought; and...
The rub comes where it says "that class of airplane". If you were seeking a Commercial Pilot Certificate with a Multiengine Land rating, you could count the 7 hours. Since you are seeking a Commercial Pilot Certificate with Single Engine Land rating, then you may NOT because the multiengine AATD does not represent the class (MEL/SEL) of aircraft in which you intend to get the certificate. So the answer is that you may count 0.
If you can get some time that is able to be logged in a ASEL simulator or training device, then you may count up to 50 hours toward the total time for Commercial ASEL.
How do I know that you are seeking ASEL instead of AMEL? Because, in order to apply for a Commercial with AMEL, you would need 5 hours of instrument training in a twin 61.129 b3(i), a two hour day VFR X-C in a twin (61.129b3(iii), and two hour night VFR X-C in a twin (61.129.b3(iv), 10 hours of solo in a twin or supervised PIC (61.129b4,...
There are innumerable problems when students start mixing time. There are cases where a Private Pilot could not take a Comm ASEL because some of his/her training time was in a twin, nor could he/she take the Comm AMEL check ride because some of the training time was in a single. Not fair, it would seem, but that is the way that it is.
None of this refers to additional ratings once you have a Commercial Pilot Certificate. For that, you would examine 61.63 which has virtually no time requirements.