There are several.
Firstly, there is the time limit for thedefinitive elimination of the entry of the conviction in the criminal record according to art. 369 CP. After the expiry of this period, the registration is definitively deleted and cannot be reconstituted.
In the case of an 18-month suspended prison sentence, the entry will be deleted after 10 years (Art. 369 para. 3 PC).
Secondly, there is a period of time after which the entry in the criminal record – even if it is still entered – is no longer visible or mentioned on the extract from the criminal record for individuals according to Art. 371 CP. This is the extract you ask for in some job searches for example.
In the case of an 18-month suspended sentence for 2 years, the conviction will no longer appear in the extract from the criminal record for private individuals once the convicted person has successfully completed probation, in this case 2 years after the conviction.
Please note, however, that this conviction will remain on the criminal record if this record contains another judgment for which the time limit has not yet expired (art. 371 para. 5 PC).