That the assignees, or the persons deriving title under them, will at all times, from the date of the conveyance or other date therein stated, duly pay all rent becoming due under the lease creating the term or interest for which the land is conveyed, and observe and perform all the covenants, agreements and conditions therein contained and thenceforth on the part of the lessees to be observed and performed:
And also will at all times, from the date aforesaid, save harmless and keep indemnified the conveying parties and their estates and effects, from and against all proceedings, costs, claims and expenses on account of any omission to pay the said rent or any breach of any of the said covenants, agreements and conditions.